Manufacture of open-hearth metal



1V0 Drawing.

ZUNITED STATES,

PATENT OFFICE.

LEWIS 1B. nnmmuu'rn, on NEW YORK, N. Y.

MANUFACTURE OF OPEN -HEARTH METAL.

v invention, such as will enable others Skilled in the art to which it appertains .to make and use the same.

My invention relates to the manufacture of open hearth steel and consists in the method of treating metal for the operating of small steel plants which necessarily buy their pig iron for their open hearth furnaces. v a

A small steel plant according to present practice charges cold pig metal into the open hearth. It is the object of this invention to combine in a workable combination a series of steps that will enable such. a plant to charge hot metal into its open hearth furnace, thereby obtaining not only a verg good metal in such a smallplant but also e ecting a large economy. 7

An open hearth furnace operating on an initial charge of 100 per cent. cold material requires twice the time for charging than if fifty per cent, or fifty-five per cent. molten material were used'and in addition to this, the labor required for handling the cold stock and the mechanical equipment for transferring it is very much greater than if it were possible to charge molten metal. In

addition to this, there is a difference of twenty per cent. and over in the time required to make a heat of steel.

Furthermore it is to be pointed out that by melting iron or steel scrap, cast or malleable iron scrap, pig iron or off grade plg 3 iron in a cupola, the sulfur content of the molten metal under resent day conditionsis so great as to pro ibit-the use of cupola metal directly in the open hearth furnace.

My invention is desi ed and intendedto overcome these difiicultles and eliminate the costs herein before enumerated and to this end I melt in an ordinary gray-iron, foun dry-cupola, a charge consisting of 100 per.

cent. steel scrap or a charge consisting of a mixture of steel scrap and cast iron scrap. The cast iron scrap may be replaced in whole or in part bymalleable iron scrap,

pig iron, or off grade products of pig iron.

or anymixtures of these various metals as Specification of Letters Patent.

Application filed J'u1y23,

Patented July 26, 1921 1920. Serial No. 398,487.

the operator may deem expedient or necessary.

Asingle cupola may be used or a number of cupolas may be used, this cupola or these ous stream, to a suitable basic lined, electric furnace, -the molten charge of which is maintained covered with a basic reducing slag. The metal from this furnace is contlnuously discharged or periodically discharged as the requirements may de- .mand into a mixer, and the metal from this mixer is run into the open hearth furnace iforming inthis furnace any desired proportion of the metallic charge..

Under these conditions the cupolas may be run at a low temperature thereby preventing a too great scouring action 'on their linings at their melting zones. Thus their life is prolonged and the labor of fettling decreased. The cupola metal will contain approximately three per cent. carbon. The necessary heat is imparted to the melt in the electric furnace to maintain the metal molten and if necessary the temperature may be increased in the electric furnace thereby increasing'its fluidit As the electric furnace is run reducing preferably continuously feed to the electric furnace basic slag forming materials consisting of to 75% CaO plus MgO, the'balance being silica and the impurities usually present such as alumina &c. and the slag is covered with. powdered coal, coke or other carbonaceous material with apractical minimum amount of air entering the furnace. Such aslag picks up no reducible oxids. In other words, this slag will contain only traces of FeO,1\1nO,l3e O' and even titanium and vanadium oxids will not remain the slag. Sulfur is primarily tric furnace, i. e. either to the metal from a single cupolain the furnace or to a mixture of cupola metals from several cupolas. The run through the electric furnace is preferably continuous to the mixer. The mixer is heated and is of any usual type to,main-. tain the metal hot while standing. The charge in a basic open hear h furnace may be, jsay 40 to 45% 2 to 65% of producing the sy cold steel scrap and c0, synthetic pig metal from the mixer. The charge in an acid lined .open hearth furnace may be, say 65% to 70% steel scrap and only to The open hearth steel is finally finished and .brought up to requirements I in the usual manner. I I It will thus be seen that the open hearth operation is either in a large measure or wholly independent of the purchase of pig metal and the reduced cost of scrap materially cheapens the open hearth process and results in an open hearth steel in every respect equal to open hearth steel made from the usual pig metal. The slag from the-electric furnaceris either continuously or intermittently removed. The cupola metal is preferably supplied continuously to the elec-' tric furnace to maintain a continuous process nthetic pig metal. The quantity of synthetic pig metal charged into i the open hearth furnace in a heat will depend upon the judgment of'the 'furnaceman.

I claim:

' 1. The method of manufacturing open a synthetic pig metal from scrap in a melting furnace, removing sulfur therefrom and charging said pig metal into an open hearth furnace,- ltreatmg said metal under ozpen. hearth conditions and finishing the metal according to requirements.

The method of manufacturing open hearth steel which comprises producing a 35 transferring. said- 'metal to a separate furnace and increasing the heat of the metal therein under basic synthetic pig metal.-

cupola metal from scra reducing conditions thereby removing sulfur and utilizing the resulting metal in an openhearth furnace for the manufacture of, steel. 3. The method of manufacturing open taming a continuous run of such metal through a bas c lined electric furnace while maintalnlng a covering thereon of baslc re ducing slag, adding silicon or manganese in 'one .of the aforesaid furnaces and thereby forming a synthetic pig metal, charging said pig metal into an open hearth furnace and forming steel therefrom in the usual manner.

4, The method of manufacturin hearth metal which comprises producing a cupola metal high in carbon content, mainopen 1 hearth steel which comprises producing one mixer metal to an open hearth furnace and utilizing saidmetal as a-sulostitute for pig .metal in open hearth operations.

In testimony that I claim the foregoing t5 as my invention, I have signed my name.

LEWIS B. LINlDEMU TH. 

